SillyTavern-extras/extensions/caption/style.css

#send_picture {
    width: 40px;
    height: 40px;
    margin: 0;
    padding: 1px;
    background: no-repeat;
    background-size: 26px auto;
    background-position: center center;
    outline: none;
    border: none;
    cursor: pointer;
    transition: 0.3s;
    filter: invert(1);
    opacity: 0.5;
}

#send_picture:hover {
    opacity: 1;
}

#img_form {
    display: none;
}

.mes img.img_extra {
    max-width: 600px;
    max-height: 300px;
    border-radius: 10px;
}

@media (max-width: 768px) {
    .mes img.img_extra {
        max-width: 100%;
    }
}

.spin {
    animation-name: spin;
    animation-duration: 2000ms;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
}

@keyframes spin {
    from {transform:rotate(0deg);}
    to {transform:rotate(360deg);}
}